<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        body,
        p {
            margin: 0;
            padding: 0;
        }

        body {
            color: #333;
            font: 12px/1.5 Tahoma;
            padding-top: 10px;
        }

        #box {
            width: 300px;
            margin: 0 auto;
        }

        p {
            margin-bottom: 10px;
        }

        button {
            margin-right: 5px;
        }

        label {
            width: 5em;
            display: inline-block;
            text-align: right;
        }

        input {
            padding: 3px;
            font-family: inherit;
            border: 1px solid #ccc;
        }

        #div1 {
            color: #fff;
            width: 180px;
            height: 180px;
            background: #000;
            margin: 0 auto;
            padding: 10px;
        }
    </style>
    <script>
        var changeStyle = function (ele, name, value) {
            ele.style[name] = value;
        }
        window.onload = function () {
            var div = document.getElementById("div1");
            var btn = document.getElementsByTagName("button");
            var input = document.getElementsByTagName("input");
            btn[0].onclick = function () {
                    changeStyle(div, input[0].value, input[1].value)
                },
                btn[1].onclick = function () {
                    div.removeAttribute("style");
                }
        }
        //div.style[input[0].value] = input[1].value
    </script>
</head>

<body>
    <div id="box">
        <p><label>属性名：</label><input type="text" value="background" /></p>
        <p><label>属性值：</label><input type="text" value="tan" /></p>
        <p><label></label><button>确定</button><button>重置</button></p>
    </div>
    
    <div id="div1">在上方输入框输入"属性名"及"属性值"，点击确定按钮查看效果。</div>

</body>

</html>